Detent mechanism

ABSTRACT

A rotatably adjustable shaft is detented into a number of positions by sets of spring-pressed ball detents. Each set of balls consists of a pair of balls which, through rolling friction, counter rotate, so that a spring pressed washer that biases the balls into detent position rotates with the shaft. In this manner sliding friction is substantially eliminated, with consequent elimination of frictional drag as the shaft is turned.

United StatesPatent Bidwell Oct. 30, 1973 [54] DETENT MECHANISM FOREIGNPATENTS OR APPLICATIONS [75] Inventor: Dmmld BMW", Lemon Grove, 959,3259 1949 France 74 527 Calif.

[73] Assignee: J. Pemberton, San Diego, Calif. m y Examiner-MiltonKaufman Attorney-Warren T. Jessup et al. [22] Filed: Oct. 17, 1972 [21]Appl. No.: 298,206 [57] ABSTRACT A rotatably adjustable shaft isdetented into a number. 52 US. Cl 74/527, 200/166 SD, 251/297 ofPositions y setsof Spring-pressed ball determ- 51 int. Cl G05g 5/06 Eachof balls consists of a P Of balls which, 58 Field of Search 74/527;200/166 SD, through rolling friction, counter rotate, so that a 200 1251 297 spring pressed washer that/biases the balls into detent 7position rotates with the shaft. In this manner sliding 55 ReferencesCited friction is substantially eliminated, with consequent eliminationof frictional drag as the shaft is turned,

3 Claims, 4 DrawingFigures DETENT MECHANISM DESCRIPTION OF THE DRAWINGSDESCRIPTION OF APREFERRED EMBODIMENT The dentent mechanism of thepresent invention comprises a support or frame shown generally at 10, inwhich is journaled a shaft 12 rotated by any suitable means, such as amanually operable knob 14. The shaft 12 comprises a portion of thedetentable member of the present invention and has fixedly secured to ita circular detent plate or wheel 16. The wheel 16 is provided with aseries of recesses in the form of holes 18 passing through the plate 16,which are located on a circle coaxial with the shaft 12. The frameincludes a transverse plate 20 of appreciable thickness, which has threeequiangularly spaced passages or channels 22 passing therethroughlocated at the same radius as the recesses 18 in the detent plate 16.Riding in each of the channels 22 are a pair of aligned steel balls 24and 26,- the former being of a diameter such as to engage partially intoa recess 18 and thus detent therein.-

Mounted circumjacent the shaft 12 is a disc-like plate or thurst washer28 which bears against each of the three balls 26, being biasedthereagainst by a compression spring 30, which bears against the washer28 through the intermediacy of a plastic bearing ring 32. The oppositeend of the spring 30 bears against a similar bearing ring 34 held inplace by a snap ring 36.

In the position shown in FIG. 3 the mechanism is in one of its detentedpositions, the number of such positions depending on the number ofrecesses 18 in the recess circle on the detent plate or wheel 16. Whenthe shaft 12 is turned by the knob 14, the detent wheel 16 turns withit. Since the balls 24/26 are prevented from turning about the shaft 12,being restrained in the channel 22, they are pushed axially away fromthe recess 22 toward the thrust washer 28 against the bias of the spring30, to the position shown in FIG. 4. As the next adjacent recess 18comes into line with the ball 24, the balls are detented back into theposition shown in FIG. 3. The shaft 12 is thus detent positioned at thenew setting.

Rotation of the detent wheel 16, in addition to pushing the balls 24 and26 axially in the channel 22, also causes the ball 24 to rotate about anaxis radial to the shaft 12. This is done through rolling friction.Similarly, rolling friction between the balls 24 and 26 causes ball 26to rotate in a direction opposite to 24. Finally, similar rollingfriction between the ball 26 and thrust washer 28 causes the washer 28to rotate in still the opposite direction, which is now the samerotative direction as the detent wheel 16. Thus, rotation of shaft 12produces rotation of detent wheel 16 and thrust washer 28 in the samedirection and at substantially the same speed, thereby virtuallyeliminating sliding friction typically inherent in detent mechanisms.The bearing rings 34 and 32 andthe spring 3% of necessity rotate withthe shaft 12, because they are frictionally coupled to the shaft by thesnap ring 36.

The, shaft 12, in addition to being journaled in the plate 20 at 38 isalso journaled at 39 in another cross member 40 forming a portion of theframe 10.

Adjacent the end of the shaft 12 is mounted any mechanism which is to berotatably adjusted in a detentable manner here shown as a rotary switcharm 42 carrying a contact 44 which cooperates with a series ofstationary electrical contacts not shown. These latter techniques arewell known in the art, it being understood that this mechanism may beused where any detentable member is to be actuated, whether in theelectrical, mechanical or other art. For example, shaft 12 could actuatea valve to a plurality of positions.

It will be appreciated from the above that by the use of the doubleballs 24/26, there is applied to the thrust washer 28 a rotation thesame as that of the detent plate or wheel 16. Thus, sliding friction inthe detent mechanism is substantially eliminated, with consequentminimizing of frictional drag on the shaft 12.

What is claimed is:

l. Detent mechanism comprising frame means,

a detentable member movably mounted on said frame means and having aplurality of recesses,

a pair of rotary members supported by said frame means, one of saidrotary members bearing against the other, said other member beingmovable in and out of said recesses as said detentable member is moved,and

means supported by said detentable member for biasing said rotarymembers toward said recesses.

2. Low friction detent mechanism comprising:

a frame having at least one ball channel,

a shaft rotatably mounted on said frame,

a detent plate secured to said shaft adjacent said channel and having aplurality of recesses therein facing said channel and lying on a circleregisterable with said channel as said shaft is turned,

a pair of balls aligned in said channel and bearing against each other,one of said balls being movable in and out of said recesses as: saidshaft is rotated,

rotation of said shaft causing said one ball to rotate and by frictionalso to rotate said other ball,

a' thrust washer circumjacent said shaft and bearing against said otherball, and

a compression spring circumjacent said shaft and bearing against saidthrust washer to bias said balls toward said detent plate.

3. Mechanism in accordance with claim 2 including:

a plurality of said channels, equiangularly spaced around said circleeach channel having a pair of said balls.

1. Detent mechanism comprising frame means, a detentable member movablymounted on said frame means and having a plurality of recesses, a pairof rotary members supported by said frame means, one of said rotarymembers bearing against the other, said other member being movable inand out of said recesses as said detentable member is moved, and meanssupported by said detentable member for biasing said rotary memberstoward said recesses.
 2. Low friction detent mechanism comprising: aframe having at least one ball channel, a shaft rotatably mounted onsaid frame, a detent plate secured to said shaft adjacent said channeland having a plurality of recesses therein facing said channel and lyingon a circle registerable with said channel as said shaft is turned, apair of balls aligned in said channel and bearing against each other,one of said balls being movable in and out of said recesses as saidshaft is rotated, rotation of said shaft causing said one ball to rotateand by friction also to rotate said other ball, a thrust washercircumjacent said shaft and bearing against said other ball, and acompression spring circumjacent said shaft and bearing against saidthrust washer to bias said balls toward said detent plate.
 3. Mechanismin accordance with claim 2 including: a plurality of said channels,equiangularly spaced around said circle each channel having a pair ofsaid balls.